1. Technical Field
The present invention relates to the field of RFID tags, and in particular to a RFID tag that is electromagnetically tuned to adjacent structure, for wideband operation.
2. Background Information
A radio-frequency identification (RFID) tag generally contains two main components. The first is an antenna that receives and radiates an RF signal. The second component is an integrated circuit that may be mounted to a printed circuit board. The integrated circuit processes a received signal provided by the antenna, and provides a modulated output signal to be radiated by the antenna.
The RFID tag may be an active device (i.e., it includes a battery that powers the tag) or a passive device (i.e., does not include a battery and instead relies upon energy received by the antenna to induce a current that provides a voltage to operate the RFID tag). Notably, passive RFID tags are relatively inexpensive and are used ubiquitously.
One problem with RFID ceramic based (patch) antenna technologies used in RFID tags is that they work well in only one of three regional frequency ranges specified for RFID tags. For example, the United States uses 902-928 MHz, while Japan uses 952-955 MHz and Europe uses 865-869 MHz. As a result, RFID tags are typically designed/tuned to work within a single designated frequency range associated with a certain country/region (i.e., a narrowband frequency range). The country/region dependent frequency ranges creates logistical handling issues.
There is a need for a passive RFID tag system that operates across multiple frequency ranges.